FWIW, this has long since been patched and TLS-SNI is no longer considered a valid method for ACME. It's being replaced with TLS-ALPN which doesn't have this problem: https://community.letsencrypt.org/t/tls-alpn-validation-meth...
I think you're conflating LetsEncrypt with ACME here. LE turned off the 2 methods, and added a different tls validation method last year, but neither of those are directly related to fixing the ACME spec.
TLS-SNI has been disabled for almost a year for new issuances and the final nail in the coffin is to turn it off for renewals which is happening soon. https://community.letsencrypt.org/t/important-what-you-need-...
Based on the repository's history, TLS-SNI-01 and TLS-SNI-02 appear to have been removed from the spec approximately a year ago: https://github.com/ietf-wg-acme/acme/commit/cfe118734bab3f6b...